Idioms/O

If something occurs to you, you think of it.

If someone has a one-track mind, they spend most of their time thinking about one subject.

If you speak off the cuff, you speak without planning what you will say beforehand.

If you say something "off the record", you don't want it in the public record, or reported in the media.

If you give someone information off the top of your head, you do so from memory, without checking beforehand.

If you do something off your own bat, you do it without being asked to or told to.

If something is old hat, it's old-fashioned and no longer seen as being modern and new.

If a plan or a project is on the back burner, it isn't being worked on at present, but it might be completed in the future.

If you're on the ball, you're alert and you know what's going on around you.

You can say you're doing something "on the off-chance" if you're doing it because it might lead to something that you want, even though it's not definite.

You can say "on the one hand" before describing one of two contrasting ideas, options, or opinions, and then say "on the other hand" before describing the other one.

If you say something "on the record", you say it on the understanding that it will be part of the public record, and can be reported in the media.

If you do something on the strength of certain advice or information, you do it because the advice or information suggests doing it.

If you say you're on your last legs, it can mean you're close to exhaustion, or it can mean you're close to death. If a thing is on its last legs, it's close to breaking or wearing out.

If you do something once and for all, you do it in a way that's final and it means you'll never have to do it again.

If something happens once in a blue moon, it happens very rarely.

If you say someone is "one in a million", you mean they're an exceptionally good person.

If something happens out of the blue, you're not expecting it to happen and you're surprised when it does.

If something is out of the question, it cannot be considered because it's impossible or it's not allowed.

If you're out of your depth, you're in a situation that you don't have the experience to handle, or the knowledge to understand.

Something is out-of-date if it is old and therefore no longer useful or no longer accurate.

If something like a passport or a credit card is out-of-date, it cannot be used anymore because the period during which it was valid is over.

If you're over the moon about something, you're extremely happy and excited about it.

You can say something is over the top if you think it's too extreme or it's more than a situation needs or deserves.

If something you hear or read is over your head, or goes over your head, you don't understand it because the language or the ideas are too advanced for you.